Stents are medical devices commonly used to maintain patency of diseased body vessels, such as those of the vascular and gastrointestinal systems. Stents are often delivered via a minimally invasive procedure and thereafter expanded to contact and support the inner wall of the targeted vessel. In general, most stents include a tubular shaped support structure having a plurality of interstices configured to facilitate compression and expansion of the stent.
Many stents include proximal and distal flanges or flared ends to prevent stent migration subsequent to implantation. Flanges or flares are typically set to a larger expanded diameter relative to the stent central portion and may exert a higher radial force per unit area against the vessel wall, thereby securing the stent in position. One problem with these features, however, is that the flanges or flares can damage the vessel wall if they are excessively rigid. Specifically, the crowns at the end of a flange or flare can cause perforations as the luminal wall engages the stent during peristalsis. The resulting tissue perforations may be painful and can lead to more serious complications including infection, hemorrhage, and possibly death.
Accordingly, what is needed is a stent that can apply a high radial force to maintain lumen patency and prevent migration but can also flex in response to changes in lumen shape so as to reduce the incidence of tissue perforations and pain to a patient. In particular, what is needed is a stent having soft, flexible crowns.